Cigar Lake uranium deposit

The Cigar Lake uranium deposit is located in northern Saskatchewan in the eastern part of the Athabasca basin (Fouques et al. 1986 Bruneton 1987, 1993 Cramer Smellie 1994). Similar to the Gabon ore deposits, the primary mineralization is hosted by a hydrothermally altered sandstone (Athabasca formation), above the contact with an Archean metamorphic basement at a depth of about 430 m (Fig. 2). The ore formation occurred 1360 Ma to 1550 Ma... 

Bruneton, P. 1987. Geology of the Cigar Lake uranium deposit (Saskatchewan, Canada). In Gilboy, C. F. Vigrass, L. W. (eds) Economic Minerals of Saskatchewan. Saskatchewan Geological Society, Special Publication, Regina, SK, Canada, 8, 99-119,... 

Bruneton, P. 1993. Geological environment of the Cigar Lake uranium deposit. Canadian Journal of Earth Science, 30, 653—673. 

Fouques, J. P., Fowler, M., Knipping, H. D. Schimann, K. 1986. The Cigar Lake uranium deposit - Discovery and general characteristics. In Evans, E. L. (ed) Uranium Deposits of Canada, Special Volume. Canadian Institute of Mining and Metallurgy, Regina, SK, Canada, 33, 218-229. 

Fig. 12. Transect of the ore deposit with the surrounding mineralogy and sampling points (black circles) and flow paths tested in the calculations at the Cigar Lake uranium deposit (arrows).

TouUioat P. and Beaucaire C. (1993) Geochemistry of water crossing the Cigar Lake uranium deposit (Saskatchewan, Canada), and use of uranium and lead isotopes as ore guides. Can. J. Earth Sci. 30, 754—763. 

ViUcs P., Cramer J. J., Bachinski D. B., Doem D. C., and MiUer H. G. (1993) Smdies of coUoids and suspended particles, Cigar Lake uranium deposit, Saskatchewan, Canada. Appl. Geochem. 8, 605—616. 

Gauthier-Lafaye, F., Stille, P. Bros, R. 2004. The Gabon and Cigar Lake uranium ore deposits. In GlERE, R. Stillf., P. (eds). Energy, Waste, and the Environment a Geochemical Perspective. Geological Society, London, Special Publications, 236, 123-134. 

Figure 13.16 Schematic cross-section through the Cigat Lake uranium deposit, showing the U ore and host rocks, including lithologic characteristics related to hydrothermal alteration and weathering. USS and LSS denote upper and lower sandstone. Near-vertical dashed lines denote faults. Modified after J. J. Cramer and J. A. T. Smellie, eds.. Final report of the AECL/SKB Cigar Lake analog study. Report AECL-10851. Copyright 1994 by Whiteshell Laboratories. Used by permission.

Similar ages were obtained on Athabasca Basin deposits for mineralizations located in the vicinity of the unconformity or partly in the basement (McArthur River or Cigar Lake for example). The oldest ages obtained on uranium oxides from several deposits (i.e, Alexandre et al. 2009) have not been obtained in the present study. Such a feature could be linked either to lack of uranium deposition in the basement during this period or to the dissolution of the first U-oxides generations by later fluid circulation events. 

Fig. 4. Chondrite-normalized mean REE patterns of uranium oxides from deposits located near the unconformity (McArthur River, Cigar Lake and Shea Creek) and from basement deposits (grey zone, this study). Fayek Kyser (1997) chemical age Bonhoure (2007) and Bonhoure et al. (2007) U/Pb isotopic age.

This report concerns the application of Pb isotope geochemistry in the exploration for unconformity-type uranium deposits in the Athabasca Basin of northern Saskatchewan (Fig. 1). 2006 Pb isotope data from a number of current projects, several with U mineralization, will be discussed (Cigar Lake East, Close Lake, Midwest A, Wolly/McClean Lake, Cree-Zimmer project, and Shea Creek). 

Fayek, M., Janeczek, J. Ewing, R. C. 1997. Mineral chemistry and oxygen isotopic analyses of uraninite, pitchblende and uranium alteration minerals from the Cigar Lake deposit, Saskatchewan, Canada. Applied Geochemistry, 12,549 - 565. 

The study of the uranium deposit of Cigar Lake and of the natural nuclear fission reactors of... 

Bros, R., Gauthier-Lafaye, F., Stille, P., Ueno, K., Yoshikawa, H. Yui, M. 2003. Mechanisms of transport and retardation in clays enclosing the Cigar Lake high-grade uranium deposit (Saskatchewan, Canada). In Proceedings of Uranium Geochemistry 2003 International Conference, Nancy, 13-16 April 2003, 87-90. 

In their study of the Canadian uranium deposit at Cigar Lake, Cramer and Smellie (1994) have plotted data for K, Na+, Ca +, and Mg +, in site waters on log([M"]/[H+]") versus log[H4Si04] diagrams. In Fig. 9.15, the illite phase field is contoured to show the stabilities of different illite fractions in I/S. The plot describes the evolution of water chemistry from atmospheric precipitation and surface-waters (lakes and streams) to infiltrating soil water and groundwater above, and then in contact with, the orebody. In the soil, kaolinite and illite (the dominant clay), quartz, and feldspars are... 

Fig. 13.10, along with stability fields of stoichiometric uraninite and schoepite. The plot indicates that the intermediate oxides have a small stability range in Eh-pH space, however their stability fields occur under conditions commonly encountered in groundwater. Ahonen et al. (1993) have suggested, in fact, that their measured Eh and pH values in three drill holes in the Finnish Palmottu uranium deposit may be in equilibrium with UOj33 (U3O7) (Fig. 13.11). (See also Cramer and Smellie 1994, regarding the Cigar Lake deposit.)...

Sweden has considerable uranium reserves, with low metal content, in the Cambrian schists in the middle part of the country. Canada stands out as the most important uranium country of the world. One of the richest uranium deposits known is situated at Cigar Lake in the Canadian province of Saskatchewan. High-grade uranium ores are mined there in underground work, using water jets to cut the rock. The annual production is more than 8000 tonnes of UjOg from the rich eastern part of the ore body. 

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